Bing and even Yahoo managed to gain a bit of market share in the US in December, at the expense of Google, according to Google numbers.
It wasn't a huge growth, but the fact that Yahoo actually gained market share is remarkable and the only such occurrence in 2012.
Bing added 0.1 percentage points, to rise to 16.3 percent market share, Yahoo did the same to grow to 12.2 percent. Even AOL gained 0.1 percentage points.
This cost Google 0.3 percentage points, going from 67 percent in November to 66.7 percent in December.
The market as a whole, i.e. the total number of searches, increased in December, but Bing and Yahoo grew more than Google, relatively speaking, adding 5 percent to their search volume compared to 4 percent for Google.
Obviously, 4 percent of a huge chunk of the market is more in absolute terms than 5 percent of a tiny chunk.